Several research projects have proposed using a person's skin as an interaction surface for providing input to an electronic device. For example, as reported at the Association for Computing Machinery (“ACM”) Conference on Human Factors in Computing Systems during Apr. 10-15, 2010 in Atlanta, Ga. (“CHI 2010”), a technology called “Skinput,” which uses different body locations (e.g., fingers, arms and forearms) as interaction surfaces, was introduced. The touch input on skin surfaces of the body locations is detected by measuring the propagation of vibrations on the skin caused by movement of a person's finger against the skin surface. As reported at the ACM symposium on the User Interface Software and Technology during Oct. 16-19, 2011 in Santa Barbara, Calif. (“UIST'11”), a palm of a user's hand may be used as an interaction surface, and a touch input on the user's palm is detected using a depth camera and image processing techniques.
As reported at the Association for Computing Machinery (“ACM”) Symposium on User Interface Software and Technology during Oct. 8-11, 2013 in St. Andrews, United Kingdom (“UIST'13”), a technology called “FingerPad” makes it possible to use the skin of the fingerpad of a user's index finger as a touch surface against which the thumb can move and provide input via a pinch gesture. Tracking of the input is performed with magnetic trackers attached to the index finger and thumb. As also reported at UIST'13, a technology called “SenSkin” similarly uses the surface of the skin of a forearm of a user as an interaction surface, and tracking of a touch input on the skin of the forearm is performed using infrared sensors that detect deformation of the skin near two armbands wrapped around the forearm.